Walls are frequently damaged. It is common for buildings to settle over the course of time resulting in cracks. Old plaster may loosen and crack and start to fall off the wall or ceiling. Also, during even ordinary use, walls become damaged. Dents are formed by door knobs banged into walls, furniture which impacts walls, and children at play. In many cases, the damaged area can be repaired instead of replacing the wall.
For very small repairs, iron on patches have been used in which a polymer fabric is cut to size and ironed with a household iron set at medium heat. Compound is applied over the fabric and sanded when the compound has dried.
If the repair area is sizable, patching tape is used to help hold in the plaster. In repairing the damaged area, loose plaster or dry wall is removed, often with a screwdriver or putty knife. Slightly bending the corners of the screwdriver or knife against the wall cleans out a trough. Sandpapering may be done to provide a rough surface which adheres plaster well.
When a crack or damaged area is large, the wet plaster will not stick. The trough is fit with a mesh or perforated tape which is cut and placed into the trough. Plaster is laid over the mesh. Crisscross motions with a putty knife help to level off the plaster. Any excess plaster is squeezed out so there will not be a lump in the wall. If the patch shrinks too much as it dries, a second coat is applied. Very light sanding with 200+ to 400+ sandpaper or wiping with a dampened sponge the repaired area helps to blend in the repair with its surroundings. If the appearance of the repair is unsatisfactory, it may be brushed down with sandpaper until all edges are broken down.
The prior art repair techniques are deficient in that usually a bulge of plaster extends out from the site of the repair. Also, the prior art techniques require a large amount of scraping with a single blade. The prior art repair techniques do not remove a layer to a precise predetermined depth. When cracks are repaired by simply covering the cracks with dry wall compound, they have a tendency to reappear. Adding tape over the crack helps some, but doesn't eliminate the problem in that bulges will be visible.
Also, in putting up drywall, beveled edge panels are unavailable. It becomes necessary to join a non-beveled edge panel to another panel. Adding plaster to such a juncture results in bulging.
It would be useful to patch, join, repair and replace sections of a wall by a simple process in which the repair would blend imperceptibly with the undamaged remainder of the wall surface. A tool which would facilitate such a process would be welcome.